Reaction Time Research Articles

Vegetal Oil Transesterification Using Tetranuclear Zinc-Diterpene Clusters as the Catalysts

Organic natural products, particularly vegetal secondary metabolites, represent a highlighted source for molecules usable for many purposes, including synthesizing catalysts. Biocompatible metals can yield interesting coordination complexes to provide sustainable and valuable compounds. In the present paper, the unique in their class (μ4-oxo)-hexakis(μ2-beyerenate)-tetra-zinc(II) (1) and (μ4-oxo)-hexakis(μ2-kaurenate)-tetra-zinc(II) (2) are suggested as eco-friendly catalysts for transesterification reactions. The heterogeneous/homogeneous catalytic potential of 1 and 2 was revealed using olive oil as an equilibrated saturated-unsaturated fatty acid mixture and methanol as the nucleophile and solvent. Systematic variations in reaction conditions were achieved herein, including temperature, catalyst mass, methanol volume, and reaction time, allowing a yield of up to 97% in the transesterification process. The FAME product was characterized using 1H NMR and GC-MS, and the calorific value of 33.72 MJ/kg was concordant with the literature. The thermogravimetric, powder X-ray diffraction, and Scanning Electron Microscopy experiments complemented the catalyst properties before and after the catalytic tests. This finding suggests that coordination complexes using natural products as ligands represent a new class of potential ecological catalysts from industry and scientific research in crucial chemical reactions. Copyright © 2025 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Acidic Deep Eutectic Solvent as a Catalyst for the Esterification of Levulinic Acid to Ethyl Levulinate

Deep eutectic solvents (DESs) are environmentally friendly compounds that can be synthesized through the combination of hydrogen-bond donors and acceptors. The diverse applications of DESs underscore their potential as catalysts in various chemical reactions. In this study, an acidic DES was prepared as a catalyst for levulinic acid (LA) esterification with ethanol to produce ethyl levulinate (EL). The acidic DES was prepared from choline chloride and sulfanilic acid through thermal mixing. Characterization of the DES was conducted using Fourier transform infrared-attenuated total reflectance and nuclear magnetic resonance spectroscopy analysis to identify its functional groups and confirm the structure. Additionally, the thermal stability of the DES was analyzed using thermogravimetric analysis, while its acidity was determined using acid-base titration. The esterification of LA with ethanol was assessed under reflux conditions at 80 °C, with specific parameters examined: the molar ratio of LA to ethanol (ranging from 1:5 to 1:13), the ratio of LA to DES (ranging from 1:0.4 to 1:1.4), and the reaction duration (0.5–5 h). The DES used in this work showed an acidity of 2.89 mmol/g. The optimum conditions were obtained at a 1:7 molar ratio of LA to ethanol, a 1:1.2 ratio of LA to DES, and 3 h of reaction time at 80 °C, resulting in 99% conversion of LA to EL. This finding highlights the remarkable catalytic performance of the choline chloride/sulfanilic acid DES in facilitating a highly efficient conversion of LA to EL. Copyright © 2025 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

What can 9 million trials tell us about memorability in a hybrid search task?

ABSTRACT Hybrid visual search tasks involve searching for multiple targets held in memory, but some targets are more memorable than others. Furthermore, some items are readily identified as being in the memory set, while others are readily identified as not being in the memory set; these may be considered to vary in their “hittability” and “rejectability”, respectively. In principle, both factors should impact error rates and reaction times in hybrid search. Using a set of 9 million trials from an online hybrid search game, we analyze participants’ errors and show that hittability and rejectability are largely separable. It is possible for items to be rejectable without being particularly hittable, and to be hittable without being particularly rejectable. Both factors are consistent across participants and stable across age, training, and performance. Rejectability strongly predicted reaction times in the search for new items, while hittability was more weakly associated with reaction times.

Age and weekly physical activity are correlated with ballistic VR decision making and reaction time shooting performance at rest

Ballistic virtual reality (VR) can measure shooting performance reliably in trained and untrained subjects. The purpose of this investigation was to determine whether baseline traits such as age, habitual physical activity, and prior experience are correlated with VR decision-making and reaction time performance. Thirty participants completed a series of VR tests—Color Shapes and Steel Plates—while shooting a laser-guided and CO2-recoil fitted rifle at digitally-projected targets. The first test measured decision-making as a function of shooting a series of correct shapes (squares/triangles/circles) and colors (green/red/blue), twice, in under 2 s. The second test measured left-to-right target transition shooting skills on six, equidistant metal plates placed 7 m away from the shooting line. Age was correlated with (1) lower decision-making scores during the Color Shapes array identification test and (2) slower target transition time, smaller throughput (time/accuracy) and Hit Factor [(correct hits-misses)/time] on the Steel Plates test. Weekly physical activity had an inverse effect. A multiple regression model revealed that age and weekly activity combined predicted the Hit Factor, the most relevant shooting proficiency metric. Tactical populations scored significantly better than non-tactical in the decision-making task. Age and physical activity may plausibly predict ballistic performance, whereas tactical experience positively modulates better decision-making.

A Very Readily Prepared Ligand for Rhodium Catalysed Propene Hydroformylation.

In the search for an easy-to-make ligand that would lead to Rh catalysts that give very rare preferential formation ofiso-butanal from propene hydroformylation,bis-phosphonites andbis-phosphoramidites were designed. Catalysts derived frombis-phosphonites gave the desired lown:isoratios, but were unstable to hydrolysis.Abis-phosphoramidite ligand (EasyDiPhos) that can be made in just one synthetic step has been discovered that enables Rh-catalysed hydroformylations to proceed with unusually lown:isoratios. They were also found to have significant stability to moisture, air, and to relatively high temperatures during hydroformylation conditions. The latter was studied using a combination of High-Pressure-Infra-Red spectroscopy and NMR analysis of the catalyst resting state after 1 week under relevant conditions. Propene hydroformylation withn:isoratios well below 1 was carried out and with turnover numbers around 1000 mol/mol in one hour reaction time. One of the ligands, whilst not being the mostiso-selective example, had a partially flexiblen:isoratio depending on temperature and pressure. Two Pt(II) complexes were prepared and their X-ray crystal structures determined.The mostiso-selective catalyst was examined at low temperature(prioritisingiso-selectivity over rates) in hydroformylation of some other terminal alkenes with significant branched selectivity.

Flexibility of action verbs processing in Parkinson's disease.

This study aims to investigate action language processing abilities in Parkinson's disease (PD) compared to healthy controls (HCs), specifically examining whether the involvement of motor systems is influenced by task context. By focusing on implicit versus explicit task demands, the study evaluates how semantic processing differs in PD and whether these differences align with a flexible embodied cognition framework. The study analyzed the performance of participants on two tasks: an explicit task (semantic judgment task, SJ) and an implicit task (letter detection task, LD). PD outpatients (n = 31, mean age 64.58 years) referred to the Parkinson and Movement Disorders Unit of ICS Maugeri Hermitage were enrolled, along with a group of healthy controls (n = 31, mean age 64.19 years). Performance was measured through reaction times (RTs) and accuracy scores (Acc) during the processing of action verbs and abstract verbs. PD patients exhibited slower RTs and lower accuracy when processing action verbs compared to abstract verbs, but only during the SJ task. Slower RTs in the SJ task were predicted by language and executive functioning (semantic fluency) and disease progression (Hoehn and Yahr stages) for both action and abstract verbs. In the LD task, slower RTs were predicted by executive functioning for action verbs and attention (measured by Trail Making Test Part B and Stroop task) for abstract verbs. The findings suggest a context-dependent involvement of the motor system in action language processing, supporting a flexible, embodied approach to conceptual semantic processing rather than an automatic one.

Striatal functional connectivity associated with Sahaja Yoga meditation

Neuroscience research has associated meditation practice with effects on cognitive, motivational and emotional processes. These processes are mediated by several brain circuits, including the striatum and its associated cortical connections. The aim of this study was to focus on the striatum and test how its functional connectivity is affected in long-term practitioners of Sahaja Yoga Meditation. We studied differences between resting and meditation states in a group of 23 Sahaja Yoga Meditation experts. We also compared the resting state between meditation experts and a control group of 23 non-meditating participants. Functional connectivity contrasts between conditions and groups were performed using seeds in the dorsal and ventral striatum (caudate, putamen and nucleus accumbens). During meditation, compared to the resting state, meditators showed altered connectivity between the striatum and parietal, sensorimotor and cerebellar regions. Resting state in meditators relative to that of controls showed reduced functional connectivity between the left accumbens and the mid cingulate, which was correlated with reduced Simon Task interference reaction time effect in meditators. In conclusion, the striatum may play a pivotal role in the practice of Sahaja Yoga Meditation by altering attention and self-referencing, and by modulating bodily sensations. Furthermore, meditation practice could produce long-term changes in striatal connectivity.

An Experimental and Theoretical Investigation into [2π + 2π] Cycloaddition Reactions Catalyzed by a Cationic Cobalt(I) Complex Containing a Strong-Field PCNHCP Pincer Ligand.

In the past decade, metal-catalyzed [2π + 2π] cycloaddition reactions have gained significant momentum for the synthesis of substituted cyclobutanes and bicyclo[3.2.0]-heptanes. To date, earth-abundant metals that contain redox non-innocent (radical)-type ligands are most commonly used in these cycloaddition reactions, whereby the redox non-innocent ligand plays a crucial role in stabilizing the oxidation and spin-state of the metal center. Classical π-accepting ligands, however, are inactive for these transformations. Here, we report efficient [2π + 2π] cycloaddition reactions that are catalyzed by a cobalt(I) complex containing a traditional π-accepting but redox innocent PCNHCP pincer ligand. Mechanistic and computational investigations revealed a classical Co(I)-Co(III) redox cycle on the singlet spin manifold, where oxidative cyclization is the rate-limiting step. Overall, the herein developed methodology exhibits a wide substrate scope and low catalyst loadings (<1 mol %) and is compatible with a variety of functional groups while occurring under mild conditions (40-60 °C, N2) with short reaction times.

Kinetic Fluorimetric Determination of Iridium Based on the Catalytic Oxidation of Doped Carbon Dots.

In this study, multi-element doped carbon dots (DXM-CDs) were synthesized via a one-step hydrothermal method, utilizing dexamethasone sodium phosphate (DXM) injection as a precursor. The synthesized DXM-CDs exhibited ultraviolet fluorescence emission at 380nm, with a fluorescence quantum yield (QY) of 19.7%. The fluorescence intensity of DXM-CDs was quenched via oxidative degradation using KBrO3 in H3PO4 medium. The presence of Ir4+ ion catalyzed the oxidation of DXM-CDs using KBrO3, resulting in an accelerated fluorescence quenching. Based on this catalytic oxidation reaction, a kinetic fluorimetric method for the quantification of Ir4+ ions was developed. The optimum conditions obtained are 0.4 M H3PO4, 2.0mg mL- 1 of DXM-CDs, 1.0 mM KBrO3, reaction temperature of 100°C, and reaction time of 20min. Under optimized conditions, the method achieved a detection limit (3σ) of 14 pg mL- 1 and linear response was observed in the concentration range of 0.2 to 20 ng mL- 1. The developed method was successfully applied to the determination of Ir4+ ions in water samples, yielding accurate and precise results.

Mechanosynthesis of β-Naphthol Derivatives via Triflic Anhydride-Mediated Reaction of Arylacetic Acids with Arylalkynes.

The mechanosynthesis of β-naphthol derivatives was accomplished through triflic anhydride-mediated cyclization reactions of arylacetic acids with arylalkynes in moderate to good yields by ball milling at room temperature. The present protocol featured solvent-free and simple conditions, a short reaction time, and easily available and inexpensive reagents.

Potential Benefits of Tai Chi Chuan Exercise on the Cognitive Functions, Aerobic Capacity and Mood States of Older Adults: A Cross-Sectional Study

ABSTRACT Purpose The evidence of the benefits of Tai Chi Chuan on cognitive functions, aerobic capacity and mood states of older adults remain unclear. A cross-sectional study was designed to explore the potential effects of Tai Chi Chuan on these aspects. Methods A total of 50 older adults were divided into the Tai Chi Chuan (TCC) (n = 17), aerobic exercise (AEE) (n = 17), and sedentary lifestyle (SL) (n = 16) groups. Differences in P3 amplitude, P3 latency, reaction time, maximal oxygen uptake (VO2max) and mood states were observed. Results The reaction time of the subjects in the TCC group was significantly shorter than that in the SL group (p < .05). Meanwhile, the VO2max of the subjects in the TCC and AEE groups was significantly higher than that in the SL group (p < .001). The P3 amplitude of the subjects in the TCC group was significantly higher than that in the SL group (p < .01). Higher P3 amplitude and shorter latency were found among the subjects in the TCC group compared with those in the SL group (p < .05). In addition, the P3 amplitudes of the subjects at the Cz and Pz sites were significantly correlated with reaction time and VO2max. The results of the mood states test indicated that TCC improves positive mood and suppresses negative mood among older adults. Conclusions The findings suggest that TCC may provide superior benefits for the cognitive functions and psychology of older adults compared with aerobic exercises.

Synthesis, molecular docking, assessment of biological and anti-diabetic properties of benzalacetophenone derivatives

The current study compares the environmental impact of benzalacetophenone derivatives synthesized using conventional and nanomaterial-catalyzed techniques. Non-isolable thia-Michel adducts are produced when chalcone 1 reacts with thiourea thiolate anion; thiazine 2 is then obtained by cyclocondensation and dehydrogenation. Depending on the pH of the medium, hydrazine and target 1 can undergo pyrazole heterocyclization followed by N-acylation to produce compounds 3, 4, and 5. N-benzoylpyrazole derivative 6 was produced when compound 1 was allowed to condense with benzoylhydrazide. Hydroxylamine hydrochloride and chalcone 1 undergo cyclo-condensation, which releases H2O and yields an isoxazole derivative 7. After cyclizing cyanoacetohydrazide via the α, β-unsaturated system and adding a cyclic imino moiety to the cyano functionality, product 8 is produced. Thioamide derivative 9 was made by the interaction of Target 1 with thiosemicarbazide. Acid caused 1 to cyclize with 2-aminothiophenol, forming thiazapine 10. Michel’s addition initiated this process, which was followed by intramolecular cyclocondensation. Diazapines 11 and 12 were produced when compound 1 reacted with o-phenylenediamine and 3-nitro-o-phenylenediamine in a basic media. Reaction times and product yields were enhanced in several studies by using nanoparticles in place of conventional catalysts. Azoles and their derivatives are significant members of the organic chemical class due to their broad biological and pharmacological significance. All of the produced compounds exhibited strong antioxidant activity against DPPH and H2O2 radicals and noticeably higher activity against SOR and NO radicals when compared to regular ascorbic acid. Furthermore, the biological experiments that demonstrated the action of compounds 2, 3, and 10 were corroborated by molecular docking analyses utilizing the MOE software, GacH as a maltose/maltodextrin-binding protein, and acarbose as the reference ligand.

Simulating the Energy Capture Process in Push-Pull Norbornadiene-Quadricyclane Photoswitches.

Molecular switches based on the norbornadiene-quadricyclane (NBD-QC) isomer pair are among the most promising candidates for applications in molecular solar thermal energy storage (MOST). In these compounds, solar energy is captured through a photoinduced [2 + 2] cycloaddition reaction whose mechanism is only partially understood. This holds true especially for NBD derivatives containing the type of push-pull substitution pattern that was previously proven necessary to attain reasonable photoisomerization quantum yields. In the present contribution, we report a computational investigation of the photochemistry of NBD-QC switches with precisely such a substitution pattern. Static calculations provide information on the structures of the excited electronic states involved in the photoinduced cycloaddition reaction, and the topographies of the relevant ground- and excited-state potential energy surfaces. Furthermore, nonadiabatic molecular dynamics (NAMD) simulations allow an estimation of the reaction time scale and quantum yield. The simulation results paint a detailed picture of the energy capture process: the photoinduced cycloaddition reaction begins in the spectroscopically bright excited state of the molecular switch. In the model compound for which we performed NAMD simulations, ring closing takes place on a time scale of roughly 150 fs, which makes it one of the fastest known photoisomerization reactions.

Sustainable synthesis of tunable emissive sulphur-doped CDs: a synergistic approach for metal ion sensing and antimicrobial applications.

Over the last two decades, materials from the carbon family attracting increasing attention, carbon dots (CDs) have been synthesized via naturally or synthetically derived precursors, which are mostly limited to single fluorescence emission. Tunable emissive CDs have great importance in multiple applications. Therefore, in the present study, multi-emissive sulphur doped carbon dots (S-CDs) were synthesized using the leaves of Nyctanthes arbor tristis, commonly known as night-flowering jasmine (NFJ), as a precursor, by a simple acid carbonization method. Interestingly, different synthesis parameters were employed for tuning the optical properties of the S-CDs, of which the synthesis time played a vital role for tuning the fluorescence emission of the S-CDs. Bright blue (BB-CDs), yellow (Y-CDs), and cyan blue (CB-CDs) fluorescence emissions with reaction times of 1, 6, and 8 h were observed. These three CDs have emission ranges of 391, 661 and 408 nm with corresponding quantum yields of 38.96, 6.59, and 25.06%, respectively. The structural and functional morphology of all three S-CDs were analyzed using various characterization techniques. S-CDs showed both excitation dependent (BB-CDs, CB-CDs) and independent (Y-CDs) emission behavior with good photo and pH stability. Furthermore, all the S-CDs were utilized as fluorescent probes for the detection of metal ions, and BB-CDs selectively detect Fe3+, Y-CDs detect Cr6+and Mn7+, and CB-CDs detect Cr6+ and Fe3+ions with corresponding LODs of 0.1, 1.66, 0.96, 2.18 and 1.56 μg mL-1, respectively. The static quenching mechanism was observed for BB-CDs and CB-CDs, while in the case of YB-CDs, Cr6+ shows the dynamic quenching mechanism. In addition, the antibacterial behavior of all three S-CDs was analyzed against S. aureus and K. pneumoniae (Gram positive and Gram negative) bacteria. These S-CDs show good potential in metal ion sensing in environmental water samples and biological activity.

Smart Home Automation

Abstract - The Cadio application is a smart home automation solution that combines IoT technology with AI-powered tools to provide seamless management and monitoring of household equipment. It provides multi-mode management using voice commands with Google Assistant or Amazon Alexa, allowing users to operate appliances locally or remotely via the internet. The solution works with both local Wi-Fi networks and the Cadio cloud, delivering excellent connection stability and quick reaction times. The Cadio app allows users to plan activities or set timers for autonomous appliance operation, and it may be paired with sensors to provide dynamic reactions based on environmental conditions. The platform generates code using AI, allowing users to setup devices without prior programming knowledge. The system also has safe and dependable security measures, such as pin-code security and EEPROM technology for memory retention after power outages. Cadio is easy to use, inexpensive, and adaptable, making it an excellent choice for both new and experienced users. It integrates with Google Home and Amazon Alexa for improved interoperability and offers offline functioning via manual switches, assuring reliability even during network disruptions. Overall, the Cadio app demonstrates recent improvements in home automation by combining simplicity and power. Key Words: CADIO Home Automation Application, Internet of Things (IoT), ESP8266, Wireless Control, Remote Monitoring, Automation System, Smart Devices, Mobile App, Voice Control Integration, Mobile User Interface.

Sensor-Based Motorcycle Restrain System with an Integrated Automatic Brake System

This article focuses on the development and testing of a sensor-based motorcycle restraint system equipped with an automated braking mechanism. The system integrates ultrasonic sensors, a DC linear motor, and an Arduino microcontroller to enhance motorcycle safety by detecting obstacles and applying brakes automatically. A prototype was constructed using a wooden frame and bicycle wheels to emulate the motorcycle's dynamics. The braking system utilized a genuine motorcycle drum brake, and the DC linear motor was linked to activate the brake lever based on sensor feedback. LED strips and a buzzer provided visual and audible warnings, indicating the presence and proximity of obstacles. The system was tested under various conditions to evaluate its responsiveness, accuracy, and dependability. The findings revealed that the ultrasonic sensors provided precise distance measurements, allowing for a timely response in obstacle detection scenarios. The automatic braking mechanism demonstrated a 65% reduction in reaction time compared to manual braking, improving rider safety significantly. The system also managed to reduce the braking distance at speeds of 50 km/h, demonstrating its efficacy in emergency situations. Data collected during prototype testing indicated that the system effectively engaged the brake within a 10 cm detection range, issued appropriate warnings, and accurately monitored brake wear. Despite some limitations, such as environmental sensitivity and the prototype's use of simplified materials, the research underscores the system's potential to enhance motorcycle safety. Future recommendations include improving sensor reliability in adverse weather conditions, upgrading the prototype to mimic full-scale motorcycle dynamics, and incorporating additional features like traction control and rider-assist technology.

Impact of visual stimulus complexity on associative learning and associated reaction times in migraine patients

The semantic complexity and verbalizability of visual stimuli can influence associative learning. The Rutgers Acquired Equivalence Test (RAET) uses semantically rich stimuli (faces and colored fish) to assess associative learning and generalization, while a modified version, the Polygon test, employs simpler stimuli with reduced semantic content (grayscale circles and geometric shapes). Although cognitive alterations are well-documented in migraine patients during interictal periods, the impact of visual stimulus complexity on associative learning and reaction times has not been studied. Forty-one migraine patients without aura completed both the RAET and Polygon tests. Performance metrics included acquisition error ratios, retrieval and generalization error ratios, and reaction times. The two tests were compared using non-parametric statistical methods. Migraine patients demonstrated comparable acquisition performance on the RAET and Polygon test. However, reaction times were significantly longer in the Polygon test across both acquisition and test phases. Retrieval and generalization performance were also similar between tests, despite longer reaction times with semantically reduced stimuli. Migraine patients showed consistent learning performance across visual stimuli of varying semantic complexity. Prolonged reaction times with simpler stimuli suggest increased cognitive demands, potentially mitigated by cortical compensatory mechanisms that maintain learning ability under challenging conditions.

Distinct patterns of cognitive enhancement: The role of motor experience in domain-specific and general cognitive functions.

Distinct patterns of cognitive enhancement: The role of motor experience in domain-specific and general cognitive functions.

H2‐Assisted Synthesis of Nickel Phosphide Nanocatalysts for the Hydrogenation of Phenylacetylene at Low Temperature

Nickel phosphide nanoparticles are used as catalysts in a wide range of chemical transformations such as hydrogenation. However, the synthesis of colloidal dispersion of these nanoparticles usually requires high reaction temperature and oleylamine as a reducing agent, which compromises their surface reactivity. This work reports a robust synthesis of nickel phosphide nanoparticles assisted by H2 and at the low temperature of 200 °C. Well‐crystallized Ni12P5 and Ni2P nanoparticles of 5.5±0.5nm were successfully prepared using tri‐n‐octylphosphine (TOP) as the phosphorus source. A higher temperature, reaction time and TOP/Ni ratio favored the formation of the Ni2P phase over Ni12P5. These nanocatalysts were used for the hydrogenation of phenylacetylene. At high temperature (80°C and 100°C), they allowed its full conversion to ethylbenzene. Interestingly, they were also active in the lower temperature regime, at 30°C or even 0°C, where significant conversion were obtained as soon as at least 0.1 equiv. of tri‐n‐butylphopshine was added as a co‐catalyst and styrene was the major product. The activity at low temperature outperformed these reported for other nickel phosphide nanoparticles with similar size, but prepared in the presence of oleylamine. This work highlights the relevance of H2‐assisted synthesis for the production of nanocatalysts active at temperatures below 30°C.

Determination of Phosphate as an Ion-Association Complex of 11-Molybdovanadophosphate and Diindodicarbocyanine Based on Selective Oxidation of Excess Dye

The elimination of absorbance of excess dye by selective oxidation was first proposed for analytical methods using the formation of ion-association complexes (IAs). On this basis, a new sensitive and selective spectrophotometric method for the determination of phosphate in the form of the IA of 11-molybdovanadophosphate with diindodicarbocyanine (DIDC) was developed. Symmetric diindodicarbocyanine and diindotricarbocyanine dyes can be completely oxidized by sufficiently strong oxidizing agents such as permanganate, dichromate, cerium (IV), and vanadate. Of the three dyes investigated (DIDC, N,N’-dipropyldiindodicarbocyanine, and diindotricarbocyanine), the best results were obtained with DIDC. A mixture of molybdate, vanadate, and nitric acid was preferably used as an oxidizing agent. Selective decolorization of only free dye ions, as well as changes in the IA spectrum compared to the dye spectrum, were explained by the isolation of the dye due to the formation of poorly soluble IA nanoparticles and changes in the redox potential of the dye due to its aggregation. The following optimal conditions for phosphate determination were found: 0.3 M nitric acid, 0.43 mM sodium molybdate, 0.041 mM sodium vanadate, 0.015 mM DIDC, and 18 min for the reaction time. The molar absorptivity of the IA was 1.86 × 105 mol−1·L·cm−1 at 600 nm, and the detection limit for phosphate was 0.013 µM. The developed method was applied to the determination of phosphate in natural water samples.